This invention relates generally to fuel filters which are employed in connection with internal combustion engines. More particularly, the present invention relates to fuel filters having a replaceable cartridge for removing foreign particles and for separating water from the fuel supply system of an internal combustion engine and to fuel supply systems which may require pressurization to transfer the fuel to the fuel filter.
Conventionally, fuel filters, of the type to which the invention relates, employ a disposable filter cartridge which is replaced at pre-established intervals of filter usage. The fuel filter is incorporated into the fuel supply system to the engine. The supply system may incorporate a fuel injection pump. For certain applications, it may be required to prime the filter assembly when a cartridge is replaced or when the engine is initially started. In some applications, because of the disposition of the fuel reservoir and the fuel filter or other characteristics of the fuel supply system, it may be desirable or required to impose a supply pressure to transfer or direct the fuel through the fuel filter assembly. A given fuel filter assembly configuration can have application in systems where neither a hand primer nor an automatic lift pump may be required or in applications where either one or both of such devices may be required.
For some applications it may be desirable to position the filter before the pump, such as, for example, when the filter functions as a primary filter. For other applications it may be desirable to reverse the flow through the filter, i.e., for annular filter elements to accomplish the filtering by means of a flow path flowing from the exterior to the interior. It is highly desirable for most applications to regulate the pressure, particularly to prevent excessive pressure loads on the filter element and to satisfy pressure requirements for the injection pump.